This project includes both experimental and modeling studies to investigate processes that occur during the formation and aging of small particles in the atmosphere. Small organic particles can separate into liquid phases that then can change the subsequent chemistry of the atmosphere. Experiments will be conducted to study how particle properties such as size, shape, and composition affect particle phase separation. Models will be used to study the impacts these particles have on the atmosphere.
The hypothesis of the project is that the liquid-liquid phase separation (LLPS) process is governed by the molecular composition of the particle and the particle size. This hypothesis will be tested using secondary organic aerosol (SOA) produced from the dark ozonolysis of alpha-pined and the photooxidation of 1,2,4-trimethylbenzene in a flow reactor. Particles will be collected, and their morphology will be analyzed by cryotransmission electron microscopy. The research questions that will be addressed by the proposal are the following: (1) What particle-level parameters (O:C, organic:sulfate ratio, size, etc.) determine particle morphology? (2) How does the morphology of aerosol particles evolve in time? Specifically, how do the size of particles and aging influence particle morphology? and (3) What is the impact of aerosol morphology on aerosol processes such as heterogeneous N2O5 hydrolysis? A particle-resolved modeling framework will make use of the experimental results and integrate them to quantify the relevance of the findings for atmospheric chemistry.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
